I have read as much as I could on the different threads on elbow pain. I haven’t quite found a description of what I’m experiencing so I thought I would post it. I did an upper body workout that included incline dumbbell curls, pull-ups, bench, lateral raises, decline tricep extension, seated back supported overhead press, and chest supported rows. No pain during the workout or the rest of the day. The next day I woke up to a little bit of elbow pain. This pain was minor in various positions when lifting or holding things. At full extension, no pain. At full bend (tucking my hand into my arm pit) is when I experienced the most pain. I did a full leg workout 4 days later (including squat and Romanian deadlift) and no exercises evoked any pain. It seems to be most pronounced when I did some low weight dumbbell curls and I couldn’t really feel much (if any) pain when I just did a few pull ups to try to find the pain. Barbell curls didn’t hurt as much as dumbbell curls. Tricep extensions didn’t hurt. The pain is on the inside. See below. Any thoughts?
Physiotherapist here:
Go to a physical therapist / physiotherapist.
This is a fairly non-typical elbow presentation. Whilst likely not serious, providing guiding information to you will be almost impossible without being able to physically assess you
Update: I rested it for a week. I then did a full upper body workout today with very little pain. I will update again tomorrow to see if any day after soreness or pain kicks in.
Update: The pain is beginning to resolve a bit. However, I might have identified the cause. I began my gym training doing close grip pull-ups putting a lot of tension on my arms/elbows and not engaging my back as much. I think this was too much too soon for my brachialis perhaps? So I’m transitioning to a wider grip. Hopefully this helps. Thoughts?
If brachialis was the irritated structure, that transitioning to a wider grip pull-up would help 
I get this niggle a fair bit when I push too hard on the Powertwisters.
If the picture shows a bruise, it might have been a hematoma (clotted lump of blood beneath the skin from leaky blood vessel, can be a side effect of anti-inflammatories or blood thinners or high blood pressure).
Common causes also include muscle strains, olecranon bursitis (golf ball lump of fluid reducing range) and tennis or golfers elbow (pain on mimicking a tennis shot or golf swing).
But an internet diagnosis is worth what you paid for it. Get stuff checked out if not improving quickly.
The pain has pretty much subsided. It doesn’t affect me anymore and I’m able to complete my workouts pain free. I think the lighting made it look like a bruise was there. I have identified a physical therapist that I will contact if it comes back because it seems like that is the best way to go.