Lower back pain same time everyday

So I'm 13 dpo my af is supposed to start tomorrow we bd 1 day before ovulation and 1 day after

this month is different because I everyday for about 3 days around 3PM I start getting light headed and pinching lower back pain on my right side the pain even spread to my right buttocks at times I also has creamy CM at 11 dpo which is odd for me

My boobs are always sore around af time so I can't count that

I took 2 pregnancy test this morning both negative so I'm confused ☹️