i have risk of hiv infection

hello doctor,
last week i had sex with a sex worker in thailand.she was a id card holder means registered prostitute..while having sex she was on the above position sitting on my penis ...and after a few time i noticed that i left my condom inside and penis was uncovered...she took is out then...and after that i washed my penis properly...and she was also washing her vagina again and again before and after sex...i am very scared of hiv and cant sleep since a week...i am feeling tired,,sleepy and having cold ,2 new pimple on body....i am very scared.....when shoud i get hiv test....i am really scared and feel like hell..,,.when should i get tested....pllzz plzz plzz help me.....................................