Have any of the vets done diagnostic labwork? Where is the horse from? How long has the horse been in Poland? Has this always occured when you've given regumate or is this a new occurance?
I am not at all a fan of regumate. Imagine going through your whole month's hormonal changes in a matter of hours. I have seen these mares go through dripping sweats, muscle tremors, etc etc. Messing withe the body in that manner just isn't something that should be done without serious consideration.
Licensed Veterinary Technician