Coltrane: Does sound like you may have a Herniated disc, as you suggested. Misaligned, pinched or pressured raw nerve damage is something that may not go away. One side of the hip/leg may be much weaker and one leg may be shorter than the other as a result. Every thing may seem OK and back to normal, after a while, but even turning, reaching, raising or lowering into a sitting position, etc can bring on the pain again.
Normal medical treatment will give you light 'roids, muscle relaxants, etc and tell you to take it easy with rest, hot/cold packs (pro's & con's with this). Rest is the bottom line.
A few friends of mine have used acupressure with very good results. Chiropractor adjustments may help also. Ideas is to try return the spine to near it's original state. Which does not always cure the underlining problem; nerve stress, but can go far to relieve it. When the back returns to somewhat of a normal state, I might suggest a deep sports or Rolfing massage. You ain't seen or felt nothing yet until you experience a few of those. I understand you limited funds, but some acupuncture, massage & chiropractor schools will allow advance students to work on people as a learning experence. Guy's I knew in college did this all the time.
Princess L brings up some good exercise ideas and they do strengthen the muscles involved very well. I have a background in Yoga, so am very bias in this regard for spinal flexibility, stretch and strength. If people think Yoga movements are for less than macho men, try holding some of those positions for even 20 seconds. let alone 3 to 5 minutes as some advance little old ladies students do.
The hips/butt/hams/calves/ankles form a rear lower muscle chain so working for a flex and stretch is the main focus. You want to stretch the ligaments just as well as the muscles themselves.
Stand and clasp the hands/fingers together behind the back. Place the toes on a 2X4, thick book, etc. Keeping the total back/spine straight and bend over to the front. Your not going to go very far down but the whole point is to work on the stretch, not a full ROM. Try doing these every day (not meant for a muscle size building exercise) for 20-30 stretches. Hold the bottom position for 3 to 5 seconds each rep. Do them 3 times a day.
In a few weeks the back should be strong enough to start doing light Romanian DL's, with the toes on that 2X4.,etc. Add weight as you get stronger. Can also do GoodMornings, either standing or sitting. At this point, do the heavier exercises with the feet/toes flat on the floor. Use the hands behind the back, toes on a 2X4 as a warmup movement before Romanians, GM'ing , SLDL's, regular DL's or most forms of squatting. This can insure, with a tricky back, that a range of flexibility is paid attention too.
May also want to use a warming agent or lotion on the lower back before any lifting starts. A light wrap or belt (place a small towel between the lower back and belt it's self) around the waist area can also bring warmth (and keep it there) during workouts. Good Luck.