For the 2017 tax year, taxes were due and payable by Apr 18th, 2017. No extension changes that. All an extension does is extend your time to file. It does not extend your time to pay. So if you owe taxes for 2017 and haven't paid them yet, you're late. Any outstanding balance is accumulating interest with each passing day. Unless congress changes the law (and I doubt they will for 2017, this late into 2018) that will not change regardless of your situation.
I would suggest you start paying that 2017 tax liability ASAP, even if you can't pay it all at once. That way, it shows the IRS you're making the effort, thus reducing the chances of the IRS taking other legal action against you, like placing a lein on your property or seizing bank accounts. You can make a payment online at any time at http://www.irs.gov/directpay. Just make sure you select the correct tax year you're paying, and just what type of payment it is. Then print your receipt. Without a receipt, if the IRS says you never paid, then bottom line is you never paid.
Now if you are self-employed then at this time there is no provision I'm aware of that will excuse you from paying your 2018 quarterly taxes. So you'll still need to pay those too, to the best of your ability so as to hopefully avoid any underpayment penalties next year, when you file your 2018 tax return.
With the massive changes to tax law for 2018, you really want to get the 2017 tax liabilities out of the way ASAP if you can. If things are really bad then I would suggest you seek the services of a CPA or tax professional and see if you can set up a payment plan with the IRS for your 2017 tax liability. So long as the IRS sees you're making an effort, they will generally work with you. But if you're not making the effort and they come after you, there will be no mercy.
