Kraxup

If it were me and this information was in your records there is no need for a Nexus.  Now if there is nothing in your service records then you would need to get one done.  
With that being said there is no way to say they will look at it all.  If it were me I would print the parts of your medical records and highlight where it shows it.  This way they are less prone to miss them, but this is just my opinion.

Look at it this way, when a veteran files a claim, VA is supposed to schedule him/her a C & P exam.  That C & P exam will basically say if the condition is military related or not.  Even though you were injured or were sick in the military, VA will not accept that as the cause of your condition until they get a medical opinion.  A veteran should never file a claim without a nexus letter or statement from a physician stating it is as least likely as not caused by or the result of their military service.  He/she would just be asking for VA to deny them or as Bronco said if the claim is for a presumptive condition and I have seen VA deny some of those claims.

I agree with the advise given also. Based on what info you have provided, it should not be too difficult to get a nexus letter from your doc. You could submit and take a shot without it. In all probability, the VA will rule unfavorably on some or all of your claim  and then you can go out and get more evidence for supplemental appeal. That would be a new nexus letter. Save time and aggrevation; do it beforehand IMHO.

No, a nexus is not required, however if you read many BVA decisions there appears, quite often this phrase:  "the preponderance of the evidence".   So, if you have two nexus letters from doctors/nurses and the VA has three opinions from their C&P examiners they like to say; we have more evidence against your claim than what you presented therefor, we cannot grant your claim.   The more evidence you can present, including lay evidence, the greater your chances of winning.