Do i have mono? sore throat for 8 days. white marks on my tonsils/ nodes few red spots. tested negative for strep. have had a fever for the past two days. and i think my spleen is enlarged. i feel little pressure and sharp pain only when deep breath?

The symptoms you have are more consistent with a pleuritic chest pain due to viral pleurisy vs pneumonia rather than symptoms of an enlarged spleen. Blood tests and chest X-ray can help the differential diagnosis and they should be done because you now have fever after 8 days of sore throat.

The only way to tell if you have Mono is to go see your PCP and have a complete medical examination and do a couple of blood tests to check for Mono. If the fever persists beyond 3 days then it is essential to go see your doctor and get tested including a Covid-19 test done.