Upper back pain and low grade fever.

I have been suffering from UPPER back pain and low grade fever which comes and goes for the past one month. Pain and fever started after a did some heavy lifting house work one day. I conducted Complete Blood Count and vitamin D test and my RBC and WBC were within normal range. I was diagnosed with vitamin D deficiency (Vitamin D level - 13) and have been taking Vitamin D supplements. When my fever increases, my back pain goes away but as soon as fever decreases, back pain comes back. Since last month my back pain has decreased a bit but it is still present and makes it difficult to sleep at night. I'm also a high blood pressure patient and take medicines for blood pressure. Kindly advice as to what might be causing back pain and if feber is related to back pain since according to one month old tests, I didn't have any infections. Also kindly advice what can I do to relieve pain since OTC painkillers don't work.