No cats definitely cannot take exlax or any other human OTC laxtives. You can try some cows milk as that is the best natural laxative.
You can also do an enema with a fleet but you must discard the contents it comes with and just use warm water with a half teaspoon of mineral oil. Be very carful because one jerk from her can puncture her bowel.
I know vet care is expensive - see if www.carecredit.com would finance her visit.
Please let me know if she goes from the milk. I am happy to help.