Need some savage delt destruction? Rig up a Viking press in the rack:
Let's discuss for a second. To start, for overhead pressing I always like a thumbless grip. Whether you use a thumbless grip with your bench and incline pressing is preference. But for overhead work, I've literally never seen anyone who didn't press more once they went to a thumbless grip.
With a thumbless grip, you get more of a neutral hand position and better alignment with the elbow joint. This tends to reduce stress at the shoulder and decreases torque at the elbows (because we're looking at better tension distribution across the wrist, elbow, and shoulder when you have alignment through those three joints).
The other factor here is that you're using the plate-loaded end of the barbell, so it's like using a thick bar for pressing. Thick bar work is a great option for those who have joint pain when pressing. The loading gets spread across more of the entire hand, and thus spread a bit more evenly across the forearm flexors and extensors.
When you're using a normal sized bar, with the thumbs-around style with poor wrist to elbow alignment, it can lead to elbow, biceps, and forearm pain. This is most often because of an imbalance between the muscles of the forearm or something being short and/or tight in the rotator cuff.
Try the Viking press using a (mostly) thumbless grip and see if you can do these pain free. If so, then most likely it's related to something above. But now you've got a way to at least train around it in a pain-free fashion, so you can get savage again.