Just went through the same thing except with string. I was wrapping presents and using colored string as ribbon. I had a pile of ends cut off on the table and noticed it looked a bit spread out suddenly and my cat was running away mischievously. Took him to the vet despite my husband’s protests (he didn’t want a huge vet bill over something I wasn’t sure even happened and wanted to wait and see), got X-rays, then emergency surgery. When they cut open his stomach they found that he had not only eaten the string but a jumbo hair tie as well that it had tangled with to make a huge ticking time bomb. Luckily it was caught before it hit his intestines!

Glad your kitty is alright!!