Angelfish problem

I have a pair of spawning angelfish in a tank 37 high.

ph 7.0
gh 5 kh 10
ammonia 0
nitrate 0
temp 82 F

They have laid eggs a few times before and ate them, this time my female
is swiming backwards, all day she goes backwards for about 9 inches then
lunges forward. sshaking her head hard ever other time, all day , at
first I thought this was something to do with spawning, but she has not
stopped and her tube is not out. I have looked her up and down and no
sores, no injuries, no ick or fungus. It has been non stop since this
morning. Her mate looks confused. It seems like there is something
wrong. Has anyone had this? Her seems normal, he is cleanign a leaf off,
and if she gets near it he chases her away.

The other spawns have not gone this way at all.

Kay