I bike around 2000-3000 miles a years, and have started bike-packing on some easier rail-trails.  The past few years I've gotten a pain on the inside of my elbow that seems linked to biking.  Things felt great in the winter (lots of skiing), and flared back up when getting back on the bike.  My question is if it's linked to my bike-setup with a too small frame.

I'm about 6'4", 205 lbs.  I ride a Specialized Stumpjumper with a 19" frame that I got about 15 years ago.  I was racing BMX at the time, and purposely got the small frame so I could manhandle it the way I did my BMX cruiser.  I used to keep the seat low (out of the way), with the understanding that when I really meant business I'd stand up on the pedals.  As I've gotten older (now in my early 40's), I still like my singletrack, but end up on rail-trails a lot.  To put the knees at a better angle I got an after market seatpost and cranked it way high (see attached pics).  Could this configuration be the source of my elbow pain?  I'm thinking of getting a new bike with a larger frame if it will help, but if not I'd rather save the $1k-$2k that I'd spend on the bike.