How severe is the PID?
Anyway, diving is contraindicated with PID. This is because, PID symptoms may worsen or gets exacerbated with increased pressure on the disc and this is caused by bending movements (especially in carrying heavy objects).
Carrying tanks (even worse when climbing up a boat with your whole gear on) can precipitate acute pain and worse cause the disc materials to prolapse and impinge on the nerve or spinal cord.
But then, you should check with your surgeon and perhaps do an MRI to confirm the diagnosis.
If you need further advice, please PM me.