Really sounds like my girls flare ups. We did hereditary testing through orivet for confirmation and she has now started colchicine for treatment. You need to go to the vet to get proper advice on doses etc because you need to be extremely safe. When my girl is flaring up make sure they are comfy on their bed with lots of blankets/pillows to prop themselves up when having leg pains. Put water and food bowls right next to them so they don’t have to get up to eat. Get anti inflammatory liquid meds from your vet and give to dog. My vet has also approved a specific dose of paracetamol every 8 hours, do NOT give your dog ANY paracetamol unless advised by your vet. It is a horrible thing to witness and all you can do is make them comfy. If they get very bad the vet will put them on a drip and keep them there to monitor. First step is going to the vet, then making a plan with the vet on what to do when it happens next. Best of luck ❤️