Elbow Irritation

Hey guys. I’ve been lifting for about a year and a half now and just recently for about a month I’ve been having elbow pain. Its not on the outside it seems like its in the joint almost. I can shoulder press and bench press and everything just fine, but anything thats straight tricep isolation hurts. Like for example tried to do some straight bar pushdowns, first 5 reps were fine, then after each rep the pain got worse and felt like it was burning or pinching something. I’ve been reading on it and don’t know if its lifters elbow or something else. I was wondering if just stretching would help, or working the extensors more would help if there is an imbalance.

I was just wondering what I can do to rehab and prehab?

Thanks in advance - Jack