Sorry that you're having tennis elbow and that the pain pills and creams didn't help but have you ever used the strap around your forearm? I did not believe it would work but after about 36 hours of it, I felt relief. It;s really just a strap with Velcro and it is only tight enough to hold it just below the elbow. Check you pharmacy for it. It's much simpler than anything and works great.
EW