Try giving her something to relax her. If the vet's coming back out a shot of stresnil will do the job (failing that, get a couple of cans of beer or ale into her - pour them into a bucket, she should drink it) she'll lie down, possibly outside ? but you'll be able to get a couple of stronger piglets latched and suckling
As Beewyched has said, it'll trigger the natural oxytocin response from her and should help 'flush' her womb. If she's had a jab of oxy and nothing has happened for more than an hour and she still seems distressed - you'll have to try going in to check there's not a piglet stuck and blocking the way. Wash your hands (or put on a long sterile glove) use plenty of lubricant and just gently slide your hand in (between contractions) to see if you can feel anything.
When the piglets are suckling you'll need to stay there the whole time and supervise. Also try the sqeezy sports bottles filled with some water or water/fruit juice mix to encourage her to drink - put the bottle right into her mouth and hold her head up to help her.
Keeping everything crossed for you and your sow
Keep us posted, Karen x