Annoying cousins making weird comments

Recently one of my cousins invited us over and everyone in my family was busy and I wasn’t feeling good. I told him and said I’ll let him know in a couple hours if I feel good and maybe then I can come over (this was over the phone btw so he could tell from my voice and asked). He messages me within 10 minutes saying how it’s fine and we can hangout another time and I said sure thank you I’m still not feeling well. Later found out they didn’t want us over anymore because of something else.

Well since that day whenever I’ve talked to him and said no to going somewhere he’ll joke about “are you still not feeling well”???? I’m so confused? The one time I say that I wasn’t feeling well somehow has become a joke.

Most recently they’ve been up my ass about grad school and work. I just graduated this year and I’ve been looking for a job before I start my masters program and they keep making stupid comments about how I don’t work. I don’t understand why it bothers my cousins and aunt? Funny because they’ve never worked a day outside. They’re all in their family business and one of their siblings who went grad school and all never worked a job before finishing grad school😂

I’ve worked in undergrad and been doing research and some other stuff so I’m quite busy but still they make these comments.

They’ll literally ask me what program I’m applying to every time I see them. It’s happened 5-10 times since the summer. They’ll make comments how I should only apply local while people in their family went other places. Obviously for a long time I didn’t say anything cause I do respect them but it’s so annoying. Last couple times I’ve just said “you’ll know soon” and they looked at me with shock and questioned again and I said “ya you’ll know soon”.

I don’t get why my sibling and I are always the target. They wanna know everything we do. Is there any boundaries I can set? I do try giving vague answers but they ask way too many questions