2007 G35x 5AT can't shift in "manual Mode"
 

I bought a 2007 G35x about a year ago with 132k miles and everything has been fine with it since. As of now I have 156k miles on it. Today I got into my car after finishing class and on a cold start heard a loud grind-like noise that went away after a second or 2. As I started driving, after warming it up, it was driving fine. As I got to a light I shifted into "Manual Mode", when I started driving I could not shift into 1st to 2nd and 3rd if I did not hold the shifter in the upshift position all the way. Then I could not shift into 4th gear or 5th at all. I don't know if this is a mechanical issue or computer issue since driving in D is normal and has no issues. I also noticed about a month ago when driving in D, if I tap on the gas all the way once it shifts down a gear and tap twice and shifts down 2 gears. I kinda figured it was maybe lag between gears but maybe something else? Anyone else notice similar issues with their G?