Andrew
its not good if she's off her feed, a definite sign something is not right, you say shes a bit wobbly. This could be due to over eating something like apples or pears, turnip or beet that have fermented in her tummy (is that a possibility?), she may have an ear infection which would affect her balance or worse. Personally as she is in pig i would give the vet a call, he'll probably suggest a precautionary antibiotic jab and a jab of metacam (anti inflammatory), he'll either come and do it for you and charge accordingly or if you feel proficent in jabbing her yourself go and collect the jabs from the vet. You only pay for the drugs then. They won't harm her piglets so long as you don't stress her too much and in my opinion in having lost a sow this year to blood poisoning and not spotting it in time, better safe than sorry.
HTH and she's feeling better soon.
Mandy