If you filed the first BK in 1999, it should be coming off in 2009, not 2010. Will filing again help or hurt your score? I would say it is possible it would help it.
Reason for this is simple. Your utilization will go way down, as will amounts owed, as it will all get discharged. Just be sure that, about 60 days after you file (assuming you file again) to obtain a copy of all 3 credit reports and ensure that everything is showing $0 owe and "Included in BK".
If you cannot pay the $100k (not sure how you can), then Bk is a legitimate and possibly best option. However, try to wait as long as you need to so that most if not all of the medical expenses have been incurred and you know how much you truly owe. If you file too soon and then have additional large expenses soon after you file, you won't be able to discharge those.
The new law requires you wait 8 years between bk filings, which you have done so you are ok that way. Just try and wait until you think you can turn it around so this time the bk can really help you get back on your feet.