Take your baby to the doctor. Constant fever can cause brain damage. Forget the cost, you dont want to be responsible for that!
How high is his fever right now? If it is above 102, I would take him to urgent care or the ER now. If it is lower, you probably don't need to have him seen today (unless he is having other symptoms). But, I would call his doctor in the morning and have him seen tomorrow. (Not sure where you live so I don't know what is available to you right now.) It could be something as simple as an ear infection that requires antibiotics or it could be something worse that requires more intervention. You don't want to let his fever get too high or he can have a febrile convulsion and you definitely don't want that. If he is not going to be seen right away, be sure to keep his temp down. You can put some rubbing alcohol on a cotton ball and rub his armpits or you can give him a cool bath or both. If the doctor can't see him tomorrow, I would take him to urgent care to find out what is going on.