Has mephedrone caused my rashes?

I done mephedrone quite a few times at the start of 2010 and a very short time after i stopped i started getting terrible rashes every time i bathed, at first i didn't think there was any connection but then a few months later at a party i done mephedrone again and my rashes disappeared for around a week, could my rashes be linked to me doing mephedrone? Also, how do I get rid of them? I have tried various creams, antihistamines etc but nothing helps :/