Hello Mr. Brian,
Thank you for your query at DoctorSpring.com
Amoxycillin is normally a very safe drug and well tolerated.
In rare cases, however they do give rise to symptoms such as allergic reactions, hives, rashes, red pin point spots ( very rare ). So it is possible that you're not tolerating the drug well.
Can you tell me what is the extent of the pin point spots that you have developed? And is it going on increasing? In that case it is better to stop the drug, because if you're not tolerating it well at all, you can go in for other side effects such as breathing problems, hives, swelling ( e.t.c ).
Also in case you have to change antibiotics - for how many days have you been advised Amoxycillin? What are the sinus symptoms that you have? When did the sore throat start? Do you have fever along with it?
Kindly reply to the above mentioned questions and i will get back to you,
Regards.

Hello,
I won't the attribute the sore throat so amoxycillin consumption, it is possible that it is part of the sinus infection which is getting converted to a upper respiratory tract infection. It is possible through the post nasal drip, into the throat.
However since the pin point red spots are sudden and came on after taking the medicine, it can't be neglected. I will advise you to stop the drug and i won't suggest any drug from the same class.
Rather i will advise you to take, Tab. Levofloxacin 500 mg twice daily for 7 days, it is also very effective for sinus infections as well as URTIs. I will also advise you to take Tab. Tylenol twice a day till your myalgia subsides, but take the medicine after food.
You need a prescription for the same drug, i am not sure if it is available in your cuntry without prescription. In case it is not, then get a prescription from your GP, explaining him why i advised you to change the medicine.
You also need some rest since you have this viral infection.
Feel free to discuss further,
Regards.