The pain round the front of the groin might be spd, yes. The shooting pain in the bum sounds more like sciatica, I had both, the sciatica went straight after the birth (I think it was just pressure from the baby, really)
Coping with spd... well, just not too much walking, be careful getting in and out of car/bed/bath, try to keep your knees together as much as possible and not put too much pressure on your pelvis. I don't advise using gym balls etc
There's a wealth of advice on MN about spd, do a search.
Sleeping on my side on a soft surface (I have a double duvet folded under me) with at least one pillow between my legs (I have to use two pillows) to support my pelvis has made a huge almost instant difference to my SPD. It make a difference between a painful day and a good day. I know you are going camping but can you take extra pillows with you? not do too much walking and take regular stops for stretching your legs while traveling. Also not carrying/ lifting heavy weights!?
Jamesandthegiantbanana, do you really not advise using gym balls? I find this is the only thing I can bear to sit on sometimes, is it possibly making me worse??
Stayfrosty, I am about 26/27 weeks too! Do you find that you can't roll over when in bed? It sort of feels like someone is tearing your pubic bone? <ouch> I would go to the drs, but when I got a referral last pg, I had to attend a 'self-help' group, in the middle of town, no transport and no childcare, so couldn't go!!
Stretch, if you feel it helps you then go for it, but I think it would have made mine a lot worse as I was in quite a bit of pain with my hip joints as well as the front of the pelvis, and even lifting a leg to get in the bath or slouching on the sofa made it very painful so I think bouncing on a ball would have irritated it even further. If you find it actually alleviates the condition then great!