pain in the left side of the back

I'm new to judo, I've been training for 2 weeks, and I have constant pain in my left shoulder and left side of my back. I can imagine why, but I don't know how to get around it. I'm tall and thin (1.95m / 6'4 and 75kg).

Even though I'm a white belt, there are two moves that always work, the harai goshi and the ippon sei with osoto gari. In both, I pass the opponent's arm over my right shoulder and throw it forward or to the side, using my shoulder and back.

Do I get used to this pain? Is it normal pain at the beginning from repeatedly straining a muscle that I'm not used to? Is there a way to get around the pain?

Thank you very much in advance!