What Causes Heat Spot In Lower Leg?

Hi,
I'm a 25 year old female, 1.68m. and 150lb. I started taking frutaplanta about a month ago. I've experienced dry mouth and a little insomnia and I'm losing weight. But, for 3 days in a row I'm experiencing a heat spot in my lower leg. It comes from the inside and when I rouch it, it's not hot. It isn't red either and doesn't hurt, but I'm starting to worry. Is it because of the pills? I have an office job and I sit for 13 hours a day. I don't do exercise, only walk long distances when I need to.
Please help.