Unless you have a need for the BigInt data type, I'd say one mistake was installing 64 bit instead of 32 bit version. With that many macros, I suspect your db is approaching the max size limit, which is 2GB. I say that because if you have that many, you probably have a lot of other forms/queries/reports that are basically the same in design where the only difference is the data they use or show. You could try opening the db in a 32 bit version to be sure that it is still ok (not corrupted). If ok, they maybe copy the db and see what happens if you use the tool to convert the macros to code. I'm assuming this can still be done in the version you have. Then delete the macros and see if all is ok. Those macros will be far from perfect, but at least you could reduce the db size. Also, did you try a compact repair on a copy to see if that improves anything?
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.