My son been sick for about 2 and half week and I took him to the doctor because at first I try to do…

My son been sick for about 2 and half week and I took him to the doctor because at first I try to do natural remedies but noting work so I took him today and they said it might not be a viral bacteria because if it been this long it a infection now so he ask me if I wanted to give him oral antibiotics or the shot I took the shot because I figure it will work faster they gave him one dose and now I have to come back tomorrow. Has anyone gave the antibiotics shot to their toddler ? And how fast did they feel better