Skin condition

Question
Hi, I have recently bought my first horse, although i have been riding for a few years. He is a 15.1hh TB gelding and is 10 year old. He is lovely to do anything with and is completely genuine yet recently when i put him in the stable for the night he kicked the bolt off the door and had obviously been crib biting. I had never seen him do that before and he has now started doing it regular. Also he has been seen licking mud. Is there a reason for this? Also he is fine in all traffic but he does have a fear of loud noises. Do you know if theres something I can do to help him trust me? He has also developed lumps under his fur which when brushed over fall out. When I looked closer it looks like little balls of something are killing off the hair. A friend said it could be sweet itch but I'm not sure as it is along his hindquarters and doesn't appear to be red or sore. Could this be possible?
Thanks,
Jade Evans
PS If you are unable to answer any of my questions I may be able to get a picture of the problem area for you.

Answer
First off, congradulations on owning your first horse! You have asked a bunch of questions today!

Cribbing & Stall Kicking:  This can be common behavior exhibited by horses experiencing anxiety and/or stress.  Stressing factors could include his recent move to your barn, paddock mates or lack of, horses stalled next door that he doesn't like or approve of. You could try changing his stall and seeing if he does better next to different horses.  Keep in mind this behavior could have been present before you owned him.  You could try contacting the previous owner and ask them what they did to minimize this behavior.  Keep in mind the are vice behaviors that due cause some medical issues down the road.  Keep him active, outdoors, munching on hay, and around horses he like to minimize this behavior.

Licking Mud:  He could be doing this as part of his instinct to farage for food.  Sometimes horses will do this because they are thirsty.  And sometimes horses do this because they are needing certain minerals lacking in their system for various reasons.  Be sure he has plenty of grass in turn out or consider putting hay out in the field for him while he out there.  Be sure he always has access to clean fresh water.  And discuss with your vet this behavior to so he/she can assess the situation properly.  It may be that he/she needs to come examine your horse's health.

Skin Condition - Sounds like Rain Rot to me, formally known as Dermatophilosis.  However, I am not a vet, nor have I examined the situation first hand.  Therefore you will definitely want to call your vet and check with him/her to provide you with a proper diagnosis.  Rain Rot is fairly common at multi horse barns.  If you are sharing any tack or leg wraps, anything that touches the affected area, then you will need to stop and use only your gear.  You will need to keep your gear clean while treating this.  The fungus thrives on carbon dioxide so brushing the clumps off is a good thing.  Sometimes the horse can become tender there so be gentle and aware of his body language to keep yourself from getting kicked.  If the fungus has not progressed too far, you can try treating it with an iodine scrub.  Scrub daily and rinse thoroughly.  Then be sure to thoroughly dry the area.  If you can't clear it with this , you can ask your vet for something stronger.