Should I feel guilty for calling in sick?

[Entropy]

I work as a nurse on a busy critical care area. I have been there for 1 year and never been off sick before, but for my night shift tonight I had to call in. I was feeling rough on my day shift but went in anyway but got progressively worse. My colleague said I sounded dreadful. I do not want to infect my colleagues or patients, some of whom have pneumonia or tracheostomies. I have a sore throat, runny nose/sinus issues, headache etc. The usual. However, I feel so guilty about having sickness on my record and making my over-budget ward have to hire an agency nurse for the shift. I have a colleague who calls in sick about once every 2 weeks. She went home ill yesterday in fact, while I was the one who was genuinely suffering and soldiered on. What do you think?