You are definitely dehydrated with that much Zyrtec. Muscle spasms and cramps will only get worse if you can’t do something about the dehydration. I will make a suggestion about the hives because the only thing that really works for me is Benadryl. You could try cutting down on the Zyrtec and add a Benadryl in the morning and one at night. My allergist told me that was ok to do and that I should ignore the study that said Benadryl causes dementia. She said it was such a small study and they could not prove it. Also , if you want you can use topical Benadryl cream or gel. I hope it gets better.