Don't EVER jumpseat while out on a sick call. You are stating you are an extra CREWMEMBER when jumpseating. The FAA could violate you for operating with an invalid medical. You make your medical certificate temporarily invalid when calling out sick. Hence you should not be on a jumpseat.

Feds should really help us by authorizing cabin seating as ok while jumpseating, but as of today you are an additional crew in any seat.