My eight-month-old baby just cut his first two teeth and is having difficulty sleeping. His teeth are through and he's not sick other than having a bit of a night-time cough, but he still keeps getting up in the night and it takes an hour or two to settle him back to sleep. I am puzzled by this because he can normally settle himself to sleep at naptime and bedtime. We tried the Ferber method and we've tried letting him cry for up to 15 minutes at a time. I'm at my wits end!
First of all, what you're dealing with is a very common (and very frustrating!) situation: baby gets sick, sleep patterns get disrupted, baby gets better, sleep patterns stay disrupted. It could be that your baby is looking for a bit of nighttime comfort, or he may simply be in the habit of waking up in the middle of the night since that became his pattern when his teeth were coming through.
It may take a little time to get your baby's sleep patterns back on track, but if you minimize the amount of interaction at nighttime (i.e., don't play with your baby when he wakes in the night), he should soon decide that being up in the middle of the night is pretty boring, so he may as well just go back to sleep.
Until he gets back on track, however, you'll need to grab bits of sleep whenever you can in order to make up for the sleep that you're missing at night. A sleep-deprived parent is not generally a very happy parent! Good luck in dealing with this challenging situation.