A lot of good Ideas have been posted.
First I would try to get your back in shape.
What did you do. REAL dammage or just a "bad" back. Upper or lower? I know, about bad lower backs. If It is lower back and the doctors can't find anything specific I have 2 recommendations
1. Go to Home depot and buy one of those back braces that the workers are supposed to wear. Put on a T shirt and wear that brace for the next week ( 24 hours a day) or untill you back gets better. That is what I used to do. As soon as I get that twinge in my lower back I put it on and usually within 3-4 days My back is fine.
2. Go out an buy the book "Healing Back Pain" by John E. Sarno M.D. Since I read this book My back has not hurt. I highly recommend it.

Jobs.
There are plenty of jobs out there. It will take some time to get out there and hunt one down. If the Home Depot brace helps you may be able to have a job that has a little more activity, Not lifting, but activity. Cashier, etc.

You need to take care of your back first. At your age having a bad back will limit your ability to live life. I know. When I was 30 I just got hired (1984) with American Airlines ( I'm now an MD80 Captain) and "threw" my back out running. I didn't attend to it immediatly and it took a couple of years to get it to recover completely.

What are you doing about becoming a Commercial pilot?
The degree in History will be adequate. Actually the Airlines do not formally require a college degree. The degree shows that you can start and complete something. And more importantly it prepares you to do something IF you can't fly. A degree in history will only allow you to teach. I would suggest a degree in business and finance. If you are science oriented, You could go that way. But getting a degree in History leads me to believe your not a Science person, More of the arts. A degree in business with a concentration in History could make you a savy investor.

What about the flying part?
What are you planning to do to get the hours required for a commercial job?
Look into the Cival Air Patrol. Military Reserves, Active duty. Or flying civilian to get your hours.

Again take care of that back. Something will come up for you, You just have to shake the trees out there.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car