it feels like i have a sore throat but theres like white lines or marks on the back of my throat. what are they?

Your symptoms are of Strep Throat or other conditions.

If you have strep throat infection, you will have a sore throat and may have white patches, lines, or marks in the back of your throat.

You can get sick within 3 days after being exposed to the germ. Once infected, you can pass the infection to others for up to 2 to 3 weeks even if you don’t have symptoms. After 24 hours of taking antibiotics, you will no longer spread the bacteria to others.

I would suggest you visited a doctor for a correct diagnosis.