I'd get an abdominal ultrasound to check liver, pancreas, gallbladder.
The pain I had with my gallbladder stones was on the left, although most people get the pain on the right. Mine was also in back instead of front.
I am most certainly not a DR but I am going thru the same...testing just revealed my liver is swollen & fatty. I don't drink, nor do drugs so thats not the reason. I am tender where you described but read it is asymptomatic...no visable symptoms. So, you might wanna get checked for it just in case. Peace & Blessings