I had a female bp do the same thing a couple of months ago, and found a similar looking lump but more towards the back of her.

I gently palpated her (as you were looking for follicles) a couple of times, I felt the mass break up, and the most disgusting moment of my herp keeping life took place immediately after.

Snakes have a relatively simple digestive track so a little massage is probably all he needs.

I would bet that mass is either a large urate or a blockage caused by one, and I have been told that large urates like that can be caused by the snake not drinking enough for whatever reasons.