No you cannot do either one of those things. You should have included ALL of your income on the same 2018 tax return. But since you did not do that, you will need to wait for the original return to be fully processed and then amend it to include the other income.
A 1040X cannot be e-filed. It must be printed and mailed. It will take about 3-4 months for the IRS to process an amended return. It is a good idea to use a mailing service that will track it, like UPS or certified mail, so you will know it was received.
Wait about 3 weeks from mailing and you can check the status of your amended return:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
https://ttlc.intuit.com/questions/1908543-do-i-need-to-amend
https://ttlc.intuit.com/questions/2566895-what-does-it-mean-to-amend-a-return
https://ttlc.intuit.com/questions/3218365-how-do-i-print-my-amended-return-if-i-ve-closed-out-of-it