Any 'sickness' from flea bites?

Sometimes. Fleas can carry tapeworms & murine typhus. In some parts of the world to include the southwestern United States they can carry a bacteria called yersinia pestis which can cause bubonic plague.
No. Flea bites (unlike tick bites) do not usually carry any diseases. There are very rare cases of plague from flea bites in rural parts of New Mexico, CA, Colorado and Arizona. Biggest risk from flea bites is itching and secondary infection. Avoid scratching. Use topical antibacterial ointment. Can take antihistamine such as Benadryl (diphenhydramine) to help itch.