Please just remember with minis that antibiotics are not always the best thing. Too many, and you have colitis, and possibly a dead mini. My advice is the same as most others on the forum, to find a good reproductive veterinarian, even if you have to trailer several hours! There are so many possibilities, that you could play around with it for years longer, miss out on the foals you could have, and lose lots more money. Or, you could find a good vet, do the testing and ultrasounding, and get more immediate results. Also, have your stallion checked as well. Just because he was fertile doesn't mean he still is. He could also be carrying an infection, had some illness that rendered him sterile, or, even gotten kicked in a strategic spot, and rendered him sterile. There are just too many questions that need a good veterinarian's testing and asnwers! I wish you luck, answers, and new foals!