My son has a fungal infection of the scalp for two months now. And has been taking medication too. Anything else I can do to get rid of it?

Examine. Frequently skin problems can appear similar to each other. Your son needs to be examined to ensure there is not a psoriasis or eczema problem.
First... ...Make sure the diagnosis is correct. Has his scalp been tested to be sure he actually has a fungal infection? If so, is he taking an oral medication? (topical treatments rarely work on scalp fungus.) if he's on an oral med, is the dosage adequate? If it is, the fungus species may be resistant to that particular medicine, and the medicine needs to be changed.