Sore pec/side lasted 4 days after boat work. A wk later slightly sore low-mid back & groin w/ some burning in arms, legs, belly &chest. Nerve pinch?

MUSCULOSKELETAL PAI. Seems like you worked a lot the last 4 days. Usually your muscles ache but to rule out back pain with sciatica you need to see MD.
No. These symptoms are too widespread to be a nerve pinch. Gentle stretching, antiimflammatories like Motrin or Aleve, (naproxen) heat, and keeping active but not overdoing it should help.