Back pain without visible signs. No lumps, no red spots, just pain between shoulders.

Patient: I’ve been having back pain on the same spot for about a year now. It hurts and I can only ease it if someone stands on my back while I lay down. It isn’t very effective since the pain comes back after a while. It hurts the most when I spend a lot of time sitting but sometimes when I stand, too. I don’t have lumps, or any visible sign and it only hurts in the same place, between the shoulders. I haven’t used any medicine and haven’t seen any doctor yet cause I’m afraid they’ll say something is wrong. Could it be my weight? I’m 125 kg and only 18 years old. My grandma, a former doctor, says it’s because of that and from not being very active.Please help me. Is there anything I can do for that. It worries me a lot and it’s bothering.Thank you!