My best advice is to call his doctor. A fever that is going up to 103 is high especially since he's been on an antibiotic for a week and the fever is still there.
If you don't mind me asking why is he on an antibiotic?

Sorry I should have given more info, we went to a walk in clinic when all this started he had swollen glands, headaches and was tired all the time so I wanted to get him tested for Mono. The mono test was negitive but they treated him with anitibiotics for the other symptoms. Since that time we've been to our local hospitals walk in clinic twice first because of the high fever, then he started to have pain in his left side along with the fevers. He's had blood work and a ct of his abdomin that's how we found out that his spleen was enlarged.

Is his primary doctor going to send him to a gastro doctor for his liver and spleen?
My son has an enlarged spleen as well, they are monitoring it with ultrasounds and blood work.
I think calling his doctor is still the best option with a fever that is still ongoing.
Please keep us posted.