If you raise the temps to treat for ich, either lower the water or add an airstone to increase aeration in the water as the higher temps will decrease the oxygen in the water.
I agree with Wolf if the fish doesn't have white spots then it isn't ich. Is he eating normally? Answering the following questions will help us help you.
1~What type of fish is afflicted? In addition, please describe what is wrong with the fish to the best of your ability (i.e. cotton like growth, bloated, etc.).
2~What are your tank parameters (ammonia, nitrites, nitrates, temp, pH)? Please give exact values.
3~ How large is the tank? How long has the tank been set up?
4~What type of filtration are you using? Please give the name and number (i.e. Fluval 304) and amount of gph
5~How many fish are in the tank? What kinds of fish are they and what are their current sizes?
6~When is the last time you did a water change and vacuum the gravel? How often do you do this? How much water do you remove at a time?
7~How long have you had the fish? If the fish is new, how did you acclimate it/them?
8~Have you added anything new to the tank--decor, new dechlorinator, new substrate, etc.?
9~What kind of food have you been feeding your fish, have you changed their diet recently?