Are there any certain skin infections that may cause flu like symptoms or severe illness?

Yes: Yes, in fact if these are experienced you proceed to a doctors office or emergency clinic today.

Possibly: Cellulitis may extend beyond the boundries of the skin either into underlying tissues and create fasciitis, myositis, osteomyelitis, etc. The organisms can also enter the blood stream and create sepsis. You may also be seeing cutaneous manifestations of a systemic illness rather than just a skin infection.