Baha'is I have a Question?

How do you compensate for the fact that Muhammad said he was going to be the Last prophet of God?

I don't understand what you mean by "compensate", if you can't state clearly what you mean why should anyone bother answering you?
By the way I don't think you'll find many Baha's here.

Well Bobby I am not Baha'i but I believe evidence shows that the possibility of Muhammad having a mental illness is most likely. An orphan at six years old in his time and culture would have been beyond traumatic, and we now know that PTSD can, if left untreated, manifest itself in hundreds of ways including schizophrenia, depression, high blood pressure, hallucinations and seizures; it can even contribute to the development of diabetes, ulcers, I could go on forever.

To the best of my knowledge, there are two ways to "compensate" for what you are referencing. However, first it is important to mentioned that the the Quran mentions that Muhammad is the "Seal" of the prophets not the "Last".

"Mohammed is not the father of any of your men, but the Apostle of God, and the Seal of the Prophets; for God all things doth know!"
The Qur'an (E.H. Palmer tr), Sura 33 - The Confederates

The term "Seal" has been interpreted as "Last" but the Baha'i Writings state that this interpretation is incorrect.

First, as mentioned in the quotes below, Baha'u'llah - the founder of the Baha'i Faith, teaches that all the Messengers of God are one and the same ("Their unity is absolute.") so any Messenger can state that He is the "First" or the "Last", or as the Bible would state it the "Alpha" or the "Omega".

Beyond that the Writings mention that the Baha'i Revelation is the one foretold by all previous religions. Indeed, the purpose of all previous Revelations throughout all ages was to herald the coming of Bah?'u'll?h and prepare mankind for His advent. Muhammad was the last to do so, referring to Himself as the 'Seal of the Prophets', for His was the last Dispensation of the prophetic cycle of religion.

Great question...