Bad skin day - too often

Question
I have a wonderful American Bulldog, some say part pit, that is so good and smart.  My problem is her skin.  My niece had her when she was younger, I have had her a couple of years, and she is almost 2 1/2.  Ashaunna would get bumps under her skin and my niece had to put salve on them.  The bumps would come and go.  I had her several months when I noticed a blue "S" on her tummy.  I turned out to be where they tattooed her when she was spayed, but the problem was that she had loss enough hair where it was visible and is still visible today.  
  Some say only bathe a dog a couple times a year, but she needs one every one to two weeks or there is a dry doggy smell in her bed area and I have noticed my hands feeling nasty after I pet her.  I am on a tight budget so I don't have the luxury of taking her to the vet every couple of months, but she would lick and chew around her tail so much it would look brown.  The first visit was when I noticed a rash on her tummy, she was given an injection and green Keftabs for ten days.  I bought antifungal, antibacterial shampoo from the vet which seemed to keep some hair on her.  About nine months later it was back to the vet with the same problem, only I believe the rash was wet with a head.  Same treatment, which I felt was wrong because we weren't making any headway, just beginning a cycle.  
  I felt guilty one time when it looked like she had mosquito bites all over her back, but they are bumps in or under the skin, no leakage, no scaling.  I took her to a new vet because her sides looked awful and I felt she was uncomfortable, but mainly because her ear had a lot of black stuff in it and an ear cleaner was not working.  It also seems like her skin darkens sometimes with the rashes.  This vet thought it was fleas, but changed her mind to allergies.  We had Ashaunna's records faxed so we knew what she had been on before.  The new vet prescribed ear drop, which were wonderful, and I started her 500 mg chlorphenamine a week later, but I couldn't afford the spray the vet also wanted.  But I felt her condition was getting worse, so I informed the vet I was discontinuing them.  Ashaunna didn't get any better and has been licking herself more so I took her back to the vet because in addition to looking horrible with the worse case of bumps and rash on her sides, she also had nasty looking irregular red spots on the tummy and nipples.  The vet said it was staph and gave her an injection and I was to give her the antibiotic that I had here, but couldn't find it.
  I gave Ashaunna a bath and apparently they don't feel pain like we do because her sides look so painful, but she is in good spirits and the red spots on her tummy are brown-looking, apparently healing.  since I can't afford repeated trips to the vet I have been researching for what she has and for remedies, but don't want to hurt her with wrong dosages of other medications.  So, I am looking at allergies, but she is an inside dog and I feed her Beneful because of the fiber content to minimize her gas.  I know that yeast and staph are present, but flares up because of other problems, but it also sounds like it might be pyoderma or even seborrhea (hopefully not).  So what would you suggest to heal her present condition and what would you suggest to be a preventative ritual to minimize these breakouts whatever they are?  My dog and I would be so grateful to find a solution to make her feel as wonderful as she is.
I have never known a dog to pass gas excessively, belch, grind their teeth, lick their private parts, and repeatedly swallow/lick their mouths like Ashaunna does, although the grinding has lessened lately.
Thank you

Answer
Without a good exam it is hard to actually diagnose on the internet.  I can only say that if it is allergies, she may need to be on steroid medication and if there is a secondary yeast or bacterial infection, then antibiotics and anti-fungal drugs are needed. You can bathe her twice a week in a special medicated shampoo for 2 weeks to help remove anything on her skin that may be irritating.