If you were suggested folitrax i am assuming you have multiple lesions and lot of involvement. If Methotrexate(folitrax) is affecting your blood parameters there are other options too like cyclosporine, etanercept, infliximab, secucinumab, etc for better control. A raise in platelet count that you are reporting is not normally seen due to methotrexate . However, if your baseline platelet count stays high (you haven't mentioned how high is the count so i cannot comment if its concerning or not) then seeking a hematologist for ruling out thrombycytosis might be a good idea. Discuss your case with your dermatologist and he will suggest the right option.