REVISED- I developed a large neck swelling, with severe pain and sore throat at home after I had already taken a 10 day course of 300mg Clindamycin and condition worsened. Went to ER and was diagnosed with Group A Strep, CT Scan revealed soft tissue swe

Peritonsillar abcess. Sounds like you might have a Peri-tonsillar abscess, or what has been historically called Quincy. This is a moderate medical emergency that might require incision and drainage. You should seek further medical attention ASAP.
And...? After the CT scan I would have expected that you might be admitted for IV antibiotic therapy or, at the very least been started with an IM injection. You do not say what happened but if you were not treated with non oral antibiotics you may need to contact your physician for referral to an ENT specialist. You may have an abscess or at a minimum a deep cellulitis. This is an urgent matter.