3 week cycles of fever and joint sensitivity - what is wrong
My three year old, indoor (outdoor if we are outside with her) cat has been coming down with 105-106 degree temperatures and extreme rear end joint pain in 3-week cycles. We have had her in for blood tests (two vets) ultra-sounds, x-rays and antibiotics and no one seems to know what is wrong with her. She will get sick (fever and joint pain - w/fever comes lethargy) about every 3 weeks and with antibiotics, it lasts for about 3-4 days. This has been occuring for the past 4 months. Her blood tests have all come back normal, v-rays and ultra-sounds of her abdomen all come back clear - the two vets cannot figure out what is wrong with her.
I am tempted to take her to yet another vet in hopes they can think of something neither of the other two can.
She lives with our other cat - who has been completely healthy this entire time. I am worried whatever our sick cat has can and will be transmitted to the healthy one.
Can anyone shed some light on our situation? Is this some sort of metabolic or blood disease we are dealing with?