need advice

so since 2weeks me and my boyfriend started having sex. (I wasn't a virgin and he wasn't either) And the thing is he lasts reaaaallly loong and he can never finish it because after I cum my legs start shaking like crazy and if he touches me down there it tickles and if he puts it in it hurts. And I dont know why it's like that for me because other women can go on even if they came. Can you give me any advice on how to last longer or how to countinue without pain?