Treating pain with OTC nedications will only help alleviate the symptoms for a short time. It is important to obtain a medical evaluation and appropriate diagnostic tests.
The weight lifting and running you have done may be aggravating factors and you should curtail any major activity until seen by a doctor.
Tanglewood is correct in his precautionary statements regarding ibuprofen and Tylenol.
If there is any possibility of consulting a physician, that is your best option in determining the cause of your back pain and the best options for treatment.
Be careful pushing back pain! I have a lot of back / spine issues. I take some pretty heavy medication, but as far as OTC meds go, I find Liquid Gel Advil helps me the most. A couple of things to keep in mind: Ibuprofen can damage your kidneys and acetaminophen (Tylenol) can damage your liver. Prescription meds like hydrocodone have acetaminophen in them. Good luck.