flu

Assalamualaikum,I would like to ask a question regarding having flu like symptoms during the fasting month.For the first few days of Ramadan this year, I had a sore throat and phlegm(due to cough and fever) was collecting in my throat. I was informed by my friends that swallowing phlegm would invalidate the fast. After knowing this, i still swallowed my phlegm, even if they had been coughed out and is around my tongue area. I did this because I found it difficult to spit out the phlegm, for e.g. if you are in class during lessons, or you are in the midst of a conversation. The persistence of the phlegm was so much so that i decided to just swallow it and not think anything of it, as i treat it as a bodily fluid just like saliva.My question is : 1)whether my fast for those few days have been invalidated? and 2)  whether in the scenario where i am able to spit out the phlegm e.g. i am close to a toilet, and i still swallow it as i had to keep making frequent trips to the toilet, is my fast invalidated if i swallow the phlegm?Would greatly appreciate your kind assistance on this matter. Thank you.