I-601

now i am totally confused with this process, i have filed like many others on this bored an I-130 and an I-129f, i recently received information i now have to file an I-601 for goodness knows what reason, which is gonna cost another $195, i am totally confused they told me all i had to file is the two forms that i previously filed, someone please help

now i am totally confused with this process, i have filed like many others on this bored an I-130 and an I-129f, i recently received information i now have to file an I-601 for goodness knows what reason, which is gonna cost another $195, i am totally confused they told me all i had to file is the two forms that i previously filed, someone please help

There is really nothing strange on the form as it is an SOP to some applicants when INS deemed request for additional documents and in your case my best guess is that it has to do with health related problems.Either you have to prove that your vaccination is complete or INS just want to know that you have no communicable diseade such as TB,HIV (AIDS).
There is really nothing to worry on this except of course INS does not accept credit cards

no i overstayed my visa waiver and was turned away at my port of entry, could this be why i need this form