My past glasses were 300 but im using 375 con lenses, then now my glasses were 400 bc the dr. recommend it that way is it normal for me to feel dizzy?

No: First things first. Are you dizzy w/o glasses or contact lenses? If not, then incorrect lenses might be causing dizziness (also get your family doc to check for other causes of dizziness). Go back to where your glasses/contacts where made/sold & ask for re-exam of eyes or re-evaluation of glasses/contacts. With that said, i will defer to my ophthalmology colleagues for their expertise.

No: You may have been prescribed glasses that are too strong for you. Sometimes patients over focus during the glasses check resulting in a prescription that is too strong. Other causes for the dizziness can be just switching between the glasses and contacts, they cause different distortions of the vision and the brain can't compensate for that. Change in base curve of the glasses can cause problems.