Possible reason for my intense sharp lower back pains?

A few months back i was getting very sharp lower back pains continuously over maybe a week or two. it is NOT exclusive to one side, but in the middle rather. they eventually stopped and every-now and then I might feel it. Today while at school I felt just one. but tonight i was sitting at a wooden dining chair and I suddenly couldn't move it hurt so bad. no matter which position I am in it hurts. I can't walk even. I have a heating pad on it now.

Some possible contributing factors or extra info on my daily routine: Im enrolled in school so i sit a lot and walk between classes. I often sleep slouched over a desk, but these pains began before semester as well. I smoke cigarettes. A couple months back (but AFTER i got the original pains) I did acid and i'm aware that is stored in your spinal cord. I run a little everyday. I don't workout or lift heavy objects. I carry a backpack how it is meant to be. I haven't been getting a lot of sleep but like i said this has happened already before.

I guess i would like to know: Could this possibly be serious and i need to be checked out?
Might this have anything to do with the acid?

Please offer your feedback, thank you!

yes i get that too. smoking prob doesnt have much to do with it. posture is a big thing. if you sit hunched over your body is using your shoulders . and if u where sitting up straight using your back. your back will hurt so bad

Any number of things can cause back pain.

Pinched nerve
Scoliosis
arthritis
bulging disc
degenerative discs
poor posture
strain that has not got better
Weakness
pack is too heavy
poor support in shoes

It has nothing to do with the acid.

The other answers are good but something else to consider is the possibility of a kidney infection.
Yes, it should be checked out.

Also, a heating pad may make it feel better while you're using it but it actually aggravates inflammation & will make it worse long term. where there's pain there's inflammation. You need to be using ice on it.

Possible reason for my intense sharp lower back pains?