Burning vagina after sex

Ok so I’m 32 weeks pregnant and finally had sex with my husband after a month. Well we fell asleep right after and slept like babies so this morning when I woke up, it was a bit sore down there so I proceeded to shower and get ready for work. Ok not sure if it was the soap I washed my lady bits with but it burns so bad down there like if I had a urine infection or something. I really think it’s the soap that irritated my already sore vajayjay. I used Zest soap but it’s weird coz I’ve always used that soap and had no problems. Anyone else had this happen to them?