I never knew about any of the life upgrades till I discovered the one after getting the scorpion sword. is it possible to get some of the others life upgrades. Also are you only able to get them in the Past?

yes...all the lifes upgrade can only be obtained in the past..not on the present

As for the life upgrades...be careful because some are denied after a certain progression throughout the game..

http://faqs.ign.com/articles/569/569763p1.html

This website will tell you where to go to get all 9 life upgrades and that's not all...the 9 locations comes with a picture so it's impossible to get lost!

Hope it help ya!