I recently lost around 5 lbs. (now 99 lbs.) and my S/5 panties are literally falling down on me. I cannot seem to find XS/4 bikinis. I found ONE package of Hanes XS which said they were for hips 35/36 inches!!!!! They are joking, right?

Who makes these REAL smaller sizes?

I've been wearing Victoria's Secret Pink and Calvin Klein undies. If you have an outlet mall near you with a Calvin Klein outlet store, you can usually pick them up pretty cheap. Also, I find them at a lot of discount places like Loehmann's.

Target!
Or check TJ Maxx/ Marshalls for the discounted Calvin Klein ones (though, at least in my area, the intimates sections are always in total disarray)

They actually might be joking, or rather, it might not be completely accurate. I bought some XS Hanes panties a couple months ago, and they're too tight on me. I thought that was strange, because I know I checked the size chart. It's possible I got my hip measurement wrong at the time. Anyway, I bought S Hanes panties later and they fit perfectly on my 36'' hips. For both sizes, I got the bikini style as shown here, or a very similar style: http://www.hanes.com/Hanes/Products/Women-Hanes/Women_ShopByCategory-Hanes/Women_Panties-Hanes/Women_Panties_Bikini-Hanes/H42.aspx. Maybe check the style online? The one I linked says XS is 34/35.

Yeah, size charts may not be reliable, especially for stretchy/fitted things. I mostly wear Marks and Spencer underwear in UK size 8 (a 35.4" hip, according to the size chart) and they fit my 32" hips just fine. I've never tried Hanes, though.

I know Aerie (by American Eagle) offers underwear from XXS, and I just got some XXS leggings there that fit me very tightly, so that might be worth a try? They only seem to do very low-cut/hipster styles, though.

Pretty much anything from AE in XXS fits. They're super tiny, since you're a tad bigger than me, a XS may fit too.
Gap's Teeny Bikini in XS also is a good fit after a wash (their other styles run a tad larger but you may fit the low rise)
I'm also a fan of Victoria's Secret Pink (but only in the synthetic bikini which run much smaller)

I haven't tried Calvin Klein's XS, but looks like the petites here like them. Prior to trying AE's XXS, I felt like buying petite undies was even harder than buying petite pants, because at least you can alter those!

+1 for VS pink in XS! & AE.
they kind of shrink a smidge also with washing as both are all cotton.

Aerie undies fit amazing!