The Croatian international, who enjoyed a run to the final against France in Russia, was confirmed as unavailable by manager Jurgen Klopp for Sunday's game against West Ham United.
It was first thought that Lovren's late return from international action was the reason behind his absence, but speaking to Croatian outlet Sportske novosti, the centre-back opened up on the stomach issues that he has been suffering for a while.
"I cannot train at all because of stomach muscle issues. I am suffering a lot of pain and will see a specialist doctor in the Netherlands," Lovren said. "When did I start to feel it? I felt it during the World Cup. I played with pain and those three games killed me. But who wouldn't play for Croatia at such a big tournament!
"After the World Cup finished, the pain increased. I can't even sit in my car without feeling it and to get out of the car hurts like hell! I'd always grit my teeth and play for Croatia, but now I am paying the price. But no price is too high for what we achieved in Russia.
"Of course, [Liverpool] are not happy. I haven't trained since I returned from holiday. I can't. I'll reassess things after seeing the doctor in Netherlands. I have to deal with that for now and believe it will be OK. I hoped it would pass during my holiday, but it didn't. As I went for a swim, it hurt. I couldn't even rest normally."