I'm 75 Strong Female But Not Smart Enough To Know

I'm 75 strong female but not smart enough to know when to quit shoveling.snow. 1 month ago tried to move 12" of heavy stuff off deck and walkway by garage. Since then had extreme pain for 10 days lower back and into abdomen area. figure i tore some muscles etc. i still have pain now at 5wks later in lower right rib area, especially after being on my feet for few hrs. Also muscles in all the mid lumbar area want to spasm, too. Tylenol helps some. I did Advil,iceing and heat weeks ago Hot showers seem to make hurt again and then have to rest. Will the back stretches help if done more often