If they’re getting near to their time, it could be as simple as it gets tiring on the old feet, hoiking that weight around with you. Or so all my friends who’ve been pregnant tell me
It’s really not a great idea to be tipping up a pregnant ewe. If you really can’t bear to leave it alone, pick up a foot like you would a horse. But make sure the ewe is well restrained, and knows she is, so she doesn’t kick out and try to escape. Stress is much worse for them when pregnant than sore feet is
Best restraint in my view is another person holding her against a fence with her nose in a corner. Hand under her chin, holding her head horizontal, one knee in front of her shoulder, your body against hers, other leg pressing against her rear leg behind her lamb bump. Taking care not to press too hard on the lamb bump. Other hand on her rump if you can, or steadying you against the fence. If she knows she can’t move in any direction, she’ll stand calmly while the second person has a look at her feet. Gentle but firm hold above the foot, turn the foot up behind as you would a horse. Support the foot underneath as you look at it. Remember you are increasing the weight on the other three sore feet by 1/3 each as you lift one! So don’t hold it up longer than you must.