Is the pain located more in your frontal delt head?
And to make sure I understand correctly, you experience discomfort when shoulder pressing and bicep curling beyond the mid range of the rep?
I’m only taking a stab in the dark here…
But if the pain started during the get ready/“curl” portion of the exercise, and the sensation is in the front delt head, there’s a chance you may have bicipital tendonitis – or at least some type of bicipital tendon problem.
Again, this is only my guess.
If you have insurance, a trip to the physical therapist or an orthopedic specialist may be in order.
They can conduct a series of strength and mobility tests – or even prescribe other diagnostic testing like an MRI to determine what you’ve got and how to fix it.
In the mean time, here’s something you can read:http://www.wrongdiagnosis.com/b/bicipital_tendonitis/symptoms.htm#symptom_list