If you are having phlegm then you can take amoxicillin and clavulinic acid in combination and if the phlegm is too irritating and frequent the you can take Levofloxacin
tablet also, in addition.
Amoxicillin should not cause restlessness
It could be due to stomach upset
which is a very common complication with this medicine.
you can take mulivitamins with it and in addition you can take curd so that the Lactobacillus
etc goes in body which are normal fora of intestine and is destroyed by the amoxicillin.
get well soon