Take it easy and pray its sciatica instead of anything permanent. Also don't overdo it on the NSAIDs, they can make wounds and sore muscles heal slower.
1. Accept you're getting older
2. Get some NSAIDs, rest, and a hot shower
3. Get a back brace
4. Don't stoop when shoveling; squats save spines. You threw out your back because of shit form.
5. Hope and pray that your ticket to Snap City wasn't one-way.
In general, you need to constantly work on your body.
You don't need to get shredded but, if you never work out and strengthen your body and then so something physical, you might get fucked up.