Most of the symptoms mentioned by you are part of the infection process itself.You have already mentioned yourself to be strep carrier.This is the cause for your low grade fever,loss of appetite, head ache and body aches.Stomach upset may be secondary to reduced food intake or other drugs that may have been taken.The lymphatic drainage area of the throat is the neck nodes.That is why your throat infection has caused a reactive inflammation of the neck lymph nodes.Thats why your neck nodes are swollen and tender.Another point in favour of inflammatory process in the lymph nodes is tenderness.There is no need to worry.Good antibiotic coverage with supportive treatment will get you back to normal shape sooner than later.

you may be having mild recure nt sinus infection and post nasal drip might have been there and the lymph node enlargement is due to reactive hyperplasia of sinus infections
all yor sins and symptomps can be related with the sinuses
get xray pns waters view and consult ent specialist to treat it
the post nasal drip of sinuses in throat can flare inflamation of throat with superadded strepto infections
headache is aain a symptom of sinusitis
post nasal drip can fall in stomach causing stomach upset
body aches and others are also explained on sinuses disease
doxycycline 100 mg bd for 10 days will clear sinuses fast
antiallergic fexofenadine 120 mg will decrease the pnd
add antacid tds for stomach upset
apply neomycin h ointmnt in nose bd sea water 2 drops at night to prevent further allergies
can take analgesic sos for pain and bodyaches
continue 3 wk