Is there any connection between using micro-currents on the thyroid area and an increase in thyroid cancer?

I am sorry to hear about your condition. It is important to understand that microfocused ultrasound does not use electrical currents and is very precise in the layers targeted, so should not penetrate the thyroid. Even if it did, any possible influence on developing cancer would almost certainly take more than a couple of months to manifest. Best wishes for a full recovery.