Do you happen to do heavy skullcrushers? I few years ago I had a weird problem like this. I had terrible pain in the elbow region, especially the inner elbow. Several different exercises seem to aggravate it, so it was really hard to figure out what the problem was. After changing some stuff around in my workout, I finally figured out that the problem was me doing very heavy scullcrushers, causing my form to go to shit. I was allowing my elbows to flare out while performing this exercise, which is a no-no. I dropped the weight and kept strict form by making sure that my elbows were pulled in as tight as I could. After 2 or 3 weeks, the pain went away and it's never come back. Are you sure that you have tennis elbow, or golfer's elbow?