Should we be concerned for our 4 year old?

My son has gotten the illness that our whole family has had this week.  He got it first along with my husband.  He got it on Sunday and he seemed to be better on Wed but then on Thursday (today) got a fever again and slept most of the day like he did on Monday.  My husband got it on Sunday as well but it only lasted two days for him and it only lasted 24 hours for me.  Wondering if we should be worried...??  Symptoms are lethargic, tired, cold, cough, achiness .. and fever.  His fever was 103 on Monday.  It seemed to have gone away on Wed but is back today Thursday.  Anyone else experiencing this???  

[margypops]

It seems like it is going around, could be a virus, could be allergies,flu,  so many are coughing , May be a good idea if it continues to have him checked out as he may need a med.Give him plenty of liquids so he doesn't dehydrate...Let us know how he is doing..