Okay were to begin!! Thursday last week mare was getting shod, a water tap suddenly went off behind her and she spooked resulting in her leaping around knocking legs and feet off the farriers tool box ect. Checked her on Thur night and we had escaped with nothing but a scratch on her front right pastern (at the back were the pastern meets the fetlock). Fri morning everything was normal so I rode her and she was fine. Sat the front leg was a bit swollen were the cut was but not lame etc so I just went on a hack (just walking). Sun morning front right (one with cut) was swollen up around the pastern and back right was swollen at the top inside of the cannon bone and just above the fetlock on the outside, other two legs were normal. I walked her out and she was lame on a tight turn in walk, sound in walk and trot in a straight line and about 3/4 fiths lame on a circle in trot. Mon morning both front and back right legs were swollen right up to just below knee and hock, I called the vet to arrange him to come out asap. Went back to yard on Mon night and ALL legs were swollen, both rights are worse, both lefts just swollen to above fetlock and horse very sore to walk. This morning no change in both rights but left front swelling has increased to just below the knee and back left no change. Vet came out checked her over and couldnt find anything amiss minus the swollen legs of course. Bloods were taken which we will get results for in the morning and she was given a painkiller which she reacted to!! Breathing rapidly increased and she broke out in a sweat, thankfully she went back to normal after an hour. Vet thinks it may be diet related but the only change that we can think of in the past few weeks is a) we were given a new field with long marshy grass and b) she was out last Wed and it was very wet compared to usual, as in sometimes the water was up to the middle of her pastern. She just gets half a scoop of fast fibre, one scoop of Hi-Fi lite, a handfull of oats and pink powder which she has been on for about 2 months. Vet said to cut her haylage tonight incase its that as the haylage has changed in the past week but tbh its always changing and shes never reacted. Shes 4 and we've never had problems with swollen legs or lameness with her so tbh im baffled!! Anyone any ideas??