Employment Contract Question about giving notice

Hi, I've been searching the internet all day for the answer to this and I think I finally found the place that could help.  I'm currently working for an employer in IL.  I have a contract with them stating that I would give 30 days notice prior to me leaving the company.  However, since that contract was signed they have cut my hours from 40 hours per week to 37.5 hours per week.  They have also cut the ammount of PTO that I will get.  I'm wondering if those two changes will allow me to leave with just a typical 2 weeks notice instead of the full 30 days.  If it does not change that, what could the company do to me if I left after 2 weeks of notice and not the full 30.  I'm sure I'll be able to work something out with them but I just want to know what my rights are before I make any decisions.  Thanks.

Does the contract guarantee the PTO and number of hours?