Sudden milky discharge with metallic scent?

I am on CD19,and I was dry most of the day until just now when I had a sudden gush of thick milky white discharge. My discharge/CM also had a slight metallic smell.

I got my trigger shot on Friday so I should be about 3 or 4 DPO. I have also been having slight cramping and lower back pain today and I am on 200mg of progesterone daily.

Last month my luteal phase was only 5 days, despite taking progesterone to lengthen it (my luteal phase is usually about 9 days, give or take a day and my cycles are on average 25 days). I'm scared

the same thing is happening again this month because I feel like I am getting very similar symptoms.

Is this normal? What could it possibly be?

I should also say that I am currently taking antibiotics prescribed by my OB for a UTI, so I dunno if that's what is affecting the smell of my CM. Please help me figure this out. I am going crazy over it.