Arm strain

The flexor carpi ulnaris area of my left arm has been feeling like something is caught as I lay my arm out, trying to straighen it. Its been tense, at least I think, it feels like it when I touch it anyway. I sleep mostly on my left side, with my arm under my head and pillow. Its closer to my elbow too but mostly in the flexor carpi ulnaris area. Is this a strain? Is it a strain from laying on my left side too long? The catch comes and goes. Just like an idea of what could be going on with it. I have no other issues or past issues with this arm. Just a minor wrist sprain years ago. Thanks!
I don't really know what muscles are in the arm but the place Im talking about is my forearm near my elbow.

Hi. I got your reply. I think it helps some, it gave me an idea of what could be going on. When you said it could probably be an impingement, did you mean an impingement of a nerve or what? Thanks

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C:\Users\Regina\Pictures\New folder (2)\MyElbow4.jpg

Here are links to 2 photos of my arm/elbow. It'll give you a better idea of what I was talking about in my original posts.
Please know, that I know for a better answer I will have to see a doctor. Im just wanting an idea of possiblities that I could be dealing with, ahead of time.
IF you can open the links, please look at what I have pointed out. That is where my arm aches. It feels like either its caught or a cramp like feeling. It only aches when I move it. Im not sure if what I pointed out is the FCU or not.
Thanks for your help. If the links don't work, let me know. thanks