is a period of low immunity and also the increased glycogen
content in the vaginal cells predispose it to fungal ( commonly candida ) infections or bacterial infections which could be asymptomatic or with minimal symptoms .
If you are also having a white curdy discharge it is suggestive of candida infection
Or if u have increased frequency of urination or pain on passing urine it is suggestive of urinary tract infection
As for your pain in lower abdomen its called as Braxton hick contractions or false labour .
Its a way to prepare you for the true labour pains
You can do the followin for it
take a small walk
eat a snack or drink some water
relax for some time
with these steps your pain will reduce
In case the pain continues to increase you will need to contact ur gynaecologist