Leveled up too quickly in Skyrim; Enemies now too difficult

Yes, you can still save your character if you invest a lot of time in leveling blacksmithing ect. You will need a lot of cash. Sell all your items that you have hoarded over time. One big problem might be the perks, as you might have spent all of them on other stuff.

Here is what you need to do:

• Level up alchemy
  • What is the fastest way to level up my alchemy skill?
• Level up blacksmithing
  • What is an effective way to level smithing?
• Level up enchanting
  • What is the fastest way to level up my alchemy skill?

Drink or sell your potions to merchants. Enchant your weapons or jewelry and sell them back to merchants. At first this is a big money dump, but later you will actually profit form the transactions.

You can combine the leveling with training. Train and steal back your money. Later you can paralyze the trainers to pickpocket it out of them while they cannot move.

If you run out of ingredients you can wait or fast travel between the big cities and buy all the stock from alchemists (ingredients), blacksmiths (ingots and leather) and enchanters (gem stone).

Do not fight. Run away from any monsters that might kill you. For enchanting get only souls from monsters that you are able to kill (e.g. crabs around Whiterun).

Be aware that this is really boring and time consuming. The best way to do these tasks (in a new game) is during other missions. Whenever you return to a big city, buy all ingredients etc. and craft materials that you sell instantly to merchants or stash in your house.