20 month old nursing for 2-3 hours in the middle of the night.

[veghead04]

My LO has started 2am multi-hour nursing sessions nightly.   It's been a couple of weeks now that this is pretty regular -- around 5 nights each week.  She will nurse for 5 seconds, put her head down, roll around, ask to nurse again.  This goes on and on, usually until 4 or 5 am.  It's super uncomfortable for me, and completely opposite of her past night nursing -- a quick 5/10 minute nurse and then right back to sleep for hours..   We nurse on demand during the day and always before naps/sleep.  She's home with me all day, so gets plenty of attention from me.  Any suggestions as to why this is going on and what to do to curb it?  

[julesmama]

Could it be teething?  My 23 month old can and does sleep through the night on her own most nights (no sleep training or anything like that), but when the teething gets bad nothing but nursing will satisfy her.  It's definitely been an on and off thing that lasts for months with her 2 year molars - they haven't popped out yet but she'll be fine for a few days then be in agony the next.