Big Beginner Problems

I am about four months into my career as a musician, and I have not yet been able to become addicted to any major narcotic, much less go through rehab, nor have I had an affair with even one model (not even a hand model). I feel I am substantially behind my goals at this point.

I'm sorry for that and now I'll be serious.

I have read a fair amount of stuff here & elsewhere and I know this is *not* easy, yet I do have some issues I'm not sure are common. I seek comfort from the Internets.

- First thing, recurring fretting arm tightness/pain - probably tendonitis, maybe just sore muscles. Yes, I've seen a doctor: She told me to stop playing guitar. I'm not kidding. I then saw an ortho who said I didn't have CTS or any nerve issue.

I've now had two major bouts of this. I had to take several days off each time. I'm just on the back of the second, and played for two hours yesterday. The first time, my teacher & I concluded it was due to me pressing way too hard, and squeezing the neck - bad technique. The second time, I had fallen back into that habit, slowly, plus was slinging too low.

I am hoping this may be licked now. I only practice ~an hour a day normally, so it's not like I'm killing my body with overuse.

My question for the group is: How common is this?? How many beginners have such issues?

- Second thing: Certain techniques that don't "seem" they should be so hard that I just can't do. Example: Running With The D?vil intro, you play a D7G7B7 chord (simple barre), then hammer on B8D9. You're hammering with two fingers at once. I just cannot do this without accidentally muting G. I just can't. Should I expect it to be nigh impossible at my stage?

- Keeping wrist straight/curling fingers instead. This is related to my tendonitis issues also. For some stuff I can do it, for others, just can't. Another example: Chord arpeggios in Limelight chorus. The first one is similar to the example above, where you have to fret on the D & B without muting G. I have to bend my wrist a good deal to do that. A bit of this is Ok, but a lot starts to hurt (then I stop).

So, again, I know that a lot of stuff (that looks easy) simply isn't, for any beginner. I guess I'm looking for 1) tips and 2) info about how common having to deal with pain in one form or another as a beginner is.