Hello and thank your writing to HCM for your health issues!
Short answer: You do not need to worry.
Detailed answer: Ingesting a small or larger amount of plastic will not harm you as it can not be digested by the human's gastrointestinal system. Therefore, it will come out with the stool.
You state that probably you could have ingested tiny sharp pieces of plastic. Eventually this can be a problem only if they will somehow get stuck in the inner intestinal wall or tear it apart. In the last scenario, there could be some minor bleeding that will be mixed with the stool (depending on the area of the damage). Lastly, these tiny pieces could be sucked by the intestine and get into blood flow, but this is almost impossible in your case because no matter how small these tiny pieces of plastic are they are hundreds of times bigger of what the intestine is able to absorb.
Therefore, I suggest that you do not need to worry but always have a look at your stool in the next few days in order to detect any signs of blood (red one, when the damage is in
colon, the last part of gastrointestinal system) or dark brownish (when the damage is at higher levels of intestine, the blood gets metabolized and changes color) and to make sure that everything is normal.
I think you will be fine.
Thank you and good luck!