4 Year Old and Accidents

My daughter potty trained pretty easy and pretty early. Problem is at night - - - she will go months on end with no accidents and then all of a sudden one accident leads to a week or more of accidents every night, no matter how much we make her pee, limit her liquids, etc. Just by way of background, she has had a labial adhesion in the past, which caused some problems but has been cleared up by creams. But this time i don't know what it is. She has had an accident every night for the last week or so and the last few nights she is refusing to use the bathroom before bed....she will go just enough to relieve the pressure and then you can guess what happens. We have sat in the bathroom with her for nearly an hour and nothing. Tonight was it - hubby put her back in a pullup (which made her mad but she still didn't go). I dont think this is the answer but night after night after night of interrupted sleep, changing sheets and then constant laundry is wearing thin. She says her pee pee area hurts and it looks a bit red (not too bad) but she hates anything down there because it feels squishy. Please help - I will try almost anything

Just as a further piece of info, several people have said take her to the doc and she has been due to the adhesions but was not tested for a UTI, so I will call tomorrow. BUT this is only happening at night. We have no accidents during the day, she doesn't refuse the potty during the day and doesn't complain about any pain or anything.