I honestly can't jungle with him anymore; the health problems he has sends me back to base repeatedly, and I don't know how I can resolve this issue without compromising his other stats. The regeneration of health, along with less HP pots to start with, exacerbates the situation. I usually end of building the Trailblazer jungle item, and even that heal isn't solving my problem.
What can I do to be able to play him effectively again?
You don't. Hecarim, like Nautilus and Sejuani, is in a really bad place in the new jungle, and Riot's been ignoring him for a very long time. Riot needs to either:
1.) Remove the Damage debuff against monsters on his Q or 2.) Adjust the healing cap on his W against monsters.
Hec's W was already healing for embarrassingly little in the S4 jungle, and now it's just a pure joke. The new jungle just seems to emphasize all of the things that Hec was already struggling with in S4.
Learn Superior routes, use trailblazer. Profit.
Get Rangers trailblazer. That smite and the challenging one are really the only viable ones. Rangers will give you a lot of health, especially if u smite red.
Edit: also, if u smitr while spirit of dread is up, I believe you heal for part of smite's damage.
Try 0/9/21 masteries. The 3% lifesteal/spell vamp helps sustain, and the cdr and move speed help clear times. The problem with Hec is you need ranger's trailblazer to have an average clear speed, whereas other champs can take ranger's for faster-than-average clears or skirmisher's/stalker's for better dueling/ganks.
I tried a couple of routes in custom games last night and liked this one: Gromps (smite), wolves, sentinel (smite), back for Ranger's + 2 pots, red, raptors. You are now level 4 with red buff and lots of health, so you can gank or do gromp/krug as you please. With a leash you can probably do gromp (smite), Sentinel, wolves (smite), raptor, base for ranger's, red (smite), gank.
I like this better than Gromp, Sentinel, Brambleback because your buffs last longer for ganking.
Naut and Hec are my two favorite junglers. Honestly, I've tried three different builds in Masteries and Runes for Hec, and found that ditching the movement speed in favor of Flat AD gets you through the jungle better for your early clears. Overall I'm missing about 50dmg end game from my Movement quints, so it's a tough trade. I was building him Tanky in Masteries and found that the survivability is nice, but camps take forever to clear and you oom faster. I split all three mastery trees in my final Hec build, similar to my Vi build.
As for my AstroNaut - his clears are slow, but realistically once you come out of that jungle the enemy team shites themselves because his ganks are the best. His utility is dope, I wish I was more confident in my teams ability to deal damage because in the right comp Naut is naughty.
Gromp, blue sentinel, wolves, back for 
and a health por or two, then do other side, raptors, red brambleback and krugs. Once you've got the money pick up 
and then go tank as you please.
