Blood in urine after visit to vet

Kittybear went to the vet on Thursday.   She was urinating frequently and eat a lot, but losing weight.  Her glucose was 435, so the diagnosis is diabetes.  We have an appointment on Monday to learn about injections, etc.  While at the vet, they needed a urine sample and got one with the needle to the bladder.  She came home with us and displayed no problems at all yesterday.  This morning we get up to repeated, almost frantic,  trips to the litter box.  Now we notice that she is passing blood in what little urine is coming out.  She even passed a small clot, which I have in a vial to take to the vet.  We plan on taking her in as soon as the vet's office opens this morning.  Could the method of collecting her urine the other day cause blood in her urine?  The UA was normal Thursday.

Update:  Kittybear visited the vet this morning.  We had just had a routine UA done Thursday, so they were able to request a urine culture on that sample.  Should have the results of that in a few days.  In the meantime, Clavamox was prescribed, as well as Pravocin to calm the urethra wall and buprenorpO for pain as needed. I was able to take a clot in with us, which was good. The vet said even if the cytocentisis caused bleeding the bladder, it wouldn't have been to that extent.  Since she was just diagnosed with diabetes we already had an appointment scheduled for this Monday.  Hopefully, this episode will be behind us by then and we can focus on getting her glucose under control with insulin and diet.

We have held off on the pain med and the muscle relaxer, since she doesn't show any signs of distress when using the litter box.  We'll keep a close eye on her and get the other meds into her if we think she needs them.

Update:  We had our diabetes education appointment today.  Now we just need to get the prescription filled and Kittybear will start receiving twice-daily injections of insulin.  So far, the urine culture is negative.  Her vet said that the blood clots were caused by the cytocentisis.  The suspicion is that the clot was big and she had to pass it in several tries.  Under the vet's order, we have taken up the dry food.  Both Kittybear and Ruth are quite puzzled by this turn of events.  The first day, they thought they would starve to death. After 3 days, they realize they won't starve, but aren't very happy.  I want to thank everyone for the suggestions and get well wishes.