Hi I Have Felt Constantly Sick For The Past Week

Hi I have felt constantly sick for the past week I have been taking my temperature and it's normal I feel like I'm going to throw up sometimes I'm also very tired I had a baby about almost 4 months ago so I don't know if I'm pregnant again or not but I don't I mean I haven't had my period for 2 months but I don't think I'm pregnant I might be but I don't know why I've been feeling sick like this constantly