Hello, Welcome to Healthcaremagic!
You have described your symptoms in great detail but what was exact duration of your antibiotic course-- antibiotics should be taken for 5-7 days for complete clearance of infection. Further, colds are due to viruses & antibiotics have no effects on them. What was your initial diagnosis-- was it pharyngitis?
You may do as follows:
1) Take an antihistamine like Tab. Cetirizine
10 mg once a day
2) Take an OTC antipyretic
& pain reliever like Acetaminophen
or asipirin as required
3) Do warm saline gargles; drink luke warm water only
4) Take a light but nutritious diet.
Do it for 2-3 days-- you should improve; but if not, please consult an ENT specialist