First off congrats on taking the first steps Semper Fi. MEPs doctors are assholes and meant to disqualify you its their job. As far as Computer stuff in the Marine Corps. There is probably sadly a limited amount of jobs, not saying there are none but not as many as you would find in probably the Navy. Since the Air Force shut you out (they are VERY picky don't take it personal). Have you looked at anything Navy wise as far as Computer Service jobs go? If not I would STRONGLY suggest you do that. Since you went to MEPs I'm assuming you took your ASVAB how were your line scores? I would not suggest the Marine Corps. for Computer services they will give you a MOS they need you in. They will put you where they want you. Now every branch is like that but the Marine Corps is pretty well known for you not getting your top picks by any means (jobs go fast in the Corps.) So I would not suggest the Marine Corps. if you are ONLY wanting to do Computer Services. If you are fine ending up in Infantry.
BTW Communication's In the Marine Corps REQUIRES these Line Scores:
105 EL (Electronics) for your ASVAB Line Score.
I personally do not regret my decision of joining the Corps. Wouldn't change a thing if I could. Just be ready to get a Combat Orientated Job.
As far as your D/Q From Air Force. You had to have slipped up answering a question. The MEPS Doctors only know whats on the paper, unless you say something to convince them otherwise. Impossible for them to pull your medical documents they must all be provided. So you must have slipped up during your 1 on 1 interview with the Doctors. Its the ONLY way they could say anything like that is if you said something a long the lines of that.