BBT chart all over the place

[MissNatasha]

Hi Everyone I’m new here love this site
I’m 6dpo slight cramping 5-6dpo & very moody this is my first month TTC & doing a charting my Temp seems to be all over the place after ovulation, could anyone help me understand this? I do it the same time every morning before I get up ect but I do have a cold so I don’t know if that’s what would cause this?
Thanks for any replies