I get numb in my fingers and toes from ECA. When I stop ECA, the numbness stops. I only consume small amounts of caffeine when not on ECA, so I don't know if that has any effect.
I think it helps to take breaks from an ECA stack for a day or two to control the numbness. The break does not enhance the fat-burning effect, of course. The numbness never hurt me, so I would finish off a clen cycle worry-free if I were you.
Do you consume a lot of caffeine?
I'm gonna try clen in a few months. Let me know how it goes if you have the time and feel like it. Good luck.