Bms means bowel movements.
If you are eating normally but still losing weight it could be an indication of a flare.
If you can call someone or if you feel it can wait, being the bank holiday weekend, then do so.
I have had flare before with no pain anywhere just lots of rushing to the loo with blood.
If you are concerned go to the nearest a&e and explain you are waiting to have tests but are in pain and are concerned about the weight loss. They might not do much though.
Let us know how you go. Xxxxxxxxxxxxx