Friend invited me to group, bugged by quest chain permanently.

The following series of events led to my questline being bugged.


1. My alt (Sorc) had just finished ACT2 and was mapping [sandsweapt marshes]
2. I was invited into a group by a friend who needed help killing [Blackjaw, the Remnant].
3. I party-teleported to the boss but couldn't kill it with my alt-character (Sorc).
4. I went to my main (witch) and cleared it.
5. I logged in to my alt *but now I have a new quest* [Legacy of the Vaal: Travel to Jiquani's Machinarium]

6. I should have gotten quests that led me to [Jungle Ruins]

What should I do?

Please help!