S.,
Allergic reactions are not uncommon for the "caine" family (there are 6 of them, including Lidocaine) of local anesthetics and also more frequently the preservatives used in the formulations to maintain sterility (in this case methylparaben). Whether you had the preserved or the preservative-free formulation will depend on how it was administered. Since methylparaben and other preservatives cannot be given epidurally, caudally, or in the spine generally.
If you got the actaul brand name Carbocaine, then you got the 1% (1 mg/mL), 1.5% (1.5 mg/mL) or 2% (2 mg/mL) (3% is dental use only) mepivicaine strength from a company called Hospira, a management buy-out from Abbott, both reputable and high quality companies (I've been in the pharma industry 20+ years, never worked for either company, but do keep track of who gets in quality trouble).
However, doctors and nurses often use the brand name generically rather than the generic name when a generic is actually used. Although, there really aren't very many generics left on the market, so you may have gotten the brand. I tried to find a package insert posted on the web for any of the companies still left selling it (Watson and Abraxis besides Hospira), but could not. You can reach out to Hospira using the contacts on www.hospira.com and ask them to send you one.
This product has been on the market since the 1960s and has been proven safe and effictive via normal FDA requirements, although not problem-free with regards to side effects. Not sure what your symptoms were, but you can see if they match up to the labeled side effects once you get your hands on a package insert. The package insert will give you lots of information (too much really, since any package insert is terrifying) about what other patients have experienced. If you can't get the actual one from them, you can refer to the synopsis at http://www.rxlist.com/carbocaine-drug.htm check out page 3 for side effects and drug interactions. It is very important not to just consider the drug given, but also any other drugs you are on when sorting out your response to the new drug. Normally I only trust www.webmd.com and www.mayoclinic.com for medical info. Webmd didn't have anything useful, but you may also want to check out mayoclinic.com as it also had a good summary of the product.
Let me know if you need any other help sorting out the US pharma market! Hope this helps.