As the lambs change position inside, the ewe might feel full one time and eat the next. My dairy does and ewes eat right up until they go push out a baby. They might even stop and grab a bite between babies! LOL
My ewes usually eat more before lambing since the lambs are moving into the birth position and might be giving them more room for the rumen. Some ewes bag after lambing while some bag before lambing. It depends on the ewe. And just to keep you crazy it also can change with different pregnancies. The time to worry is when they start having heavy thick mucous streaming out of the vaginal opening. By then they should be laying down and pushing, then standing uo and pushing, then laying down again. If you see this behavior keep a close watch for lambs. If this behavior and the discharge goes n for several hours, then you may want to check to be sure that the lamb is not stuck or turned wrong.
When checking, wash your hands thoroughly and use some sort of lubrication jelly. I use antibacterial liquid soap. tie up the ewe or have someone hold her and gently insert just your fingertips into the vaginal opening You should be able to feed the lambs' nose and mouth. If she is straining hard, run your finger around the inside of the vaginal opening to relax the muscle. Then gently insert your fingers further in around the lamb's head and check for the feet. The forelegs should be presenting with the hooves under the chin or on either side of the lamb's face. If there are no feet anywhere, you can gently ease your hand in along the lamb's head - you may have to push the lamb back inside to get room - and feel for the forelegs. Bring them up on either side of the lamb's head. If they are stuck you may have to pull the legs up and forward but often after this is done, the ewe can deliver on her own If the lamb is too big, you will have to pull it out but but don't be too rough to soon. Better to continue massaging the inside of the vaginal opening to relax that muscle. f you have to pull, try to time the pulls with the ewe's contractions. Remember that the lamb is slimy and if you used lube it will be more slippery. If you can get hold of the forelegs and need to pull the lamb out use a towel to wrap them to give you traction on the slippery lamb.
If the lamb is presenting in a bad position you will have to push it all the way back in against the ewe who will be complaining loudly as she tries to pushes the lamb out. The reason to push the wrongly positioned lamb back inside is that you will have room to turn it into the right position for birth. At least one front leg must come out with the head in a front facing position. If it is coming backwards both rear legs must come out first. In a backwards presentation you will have to work fast and pull the lamb out quick so it doesn't smother when the cord breaks.
Probably more than you will ever need to know, but it doesn't hurt to have that knowledge ahead of time. It makes you more confident if something does go wrong to know that you can deal with it. Just stay calm. If no one is there to help you, tie the ewe to a fence post so you can work. She wants that lamb out as much as you do! LOL