Hi Jelly, I’m sorry to hear about your troubles.
First off regarding the allergies, I would get an air purifier with a HEPA filter, plug it in a corner of the room on fence it off so that Toby can’t get to it or the cord. Secondly, have you tried different types of hay? On the assumption you are feeding her timothy, try orchard grass hay as it less commonly causes reactions in people than timothy hay does. There’s also meadow, bermuda, coastal, ryegrass, oaten and wheaten you could try (though some may be harder to source). Some companies might even send out samples if that is something you’d be looking to do.
My second thought is a bit more of a stretch. She’s not happy in the new room and you are now having allergy issues, are you sure that there isn’t something in the new room itself that is effecting both of you? Perhaps some mould under carpet for example. It’s just a thought/guess.
For grooming, get a hold of her and pop her up on a small table, or secure her in a towel so that she can’t run anywhere. If you’re having trouble combing out the mats you could also trim her mane back which for the moment will help her to stay untangled longer so that you can work on gaining her trust again. How long have you been in the new house?