Sick Betta fish - possible fin rot, but unsure

Question
I got a Betta fish about a week and a half ago, and he was fine up until a few days ago - I noticed him hanging around at the bottom, back corners of the tank, but wasn't worried at first cause it had only been a week since I got him. Thought it might've been him just nervous about the new area.
Then when he was swimming around, I saw clear-ish patches on his tail, along with a few torn/broken fin bits (that I suspected where from my stupid decision to move him from bag to tank via a fish net), and black streaks starting to run through his fins.
Now, Cadmen (my Betta) is blue-scaled, with blood-red fins that had begun to develop bright-blue highlights - these black streaks do not look natural, and when he has his fins fully... flared, I guess, I can see that his fins look ragged, pretty similar to what I've read Fin Rot as looking like.
I've already gone to the store and bought some Api Liquid Fungus Cure medicine, as the research I've been doing tells me one of the only things that can fit what he is experiencing is Fin Rot, but I would really appreciate expert advice on what to do - I don't want my Betta to die after not even two weeks of getting him.

Answer
Brittaney,

Sounds like fin rot but without a picture its hard to tell. What you are using is good but I would add some aquarium salt to his water. Make sure you dissolve the salt in water before you add it to your Betta tank. If you don't, it will burn him. With the salt, it help prevent these kinds of problems. I hope he is in a tank no smaller than 2.5 gallons and has a heater. Betta's are tropical and need warm water. Set your heater to at least 82 degrees. When using meds in any tank it is a good idea to add an air stone. Here's why. When they are sick, I always turn the heater in the tank up. No higher than 86 degrees. When we raise the temperature in the tank, it depletes the oxygen. Adding the air stone puts the much need oxygen back into the tank. I never use a net with my Betta's and I have 11 adults. I always gently grab them with both hands and then move them where they need to be. All my fish are used to this and I have no problems getting them from tank to tank. Nets can do more harm than good. Continue the medication as per the instructions on the bottle, and do water changes regularly. Since they don't need filters it is very important that you do regular weekly water changes of about 25%.