Counting number of syllables in a word, but taking into account that any vowels right next to each other in a word count as one single syllable

I've been able to count number of syllables in a word by making a simple nested for loop, but can't figure out how to rewrite such an algorithm that ensures any multiple vowels right next to each other in a word count as just one syllable. I've only come across one other example using pointers, my question is if there's any other approach as I just started learning pointers this week and am not sure how to use them properly.

This is my program so far:

#include <iostream>
#include <string>


using namespace std;

void indexfx(string sentence);

int main(void)
{
   string user;
   cout << "\n\nPlease Enter a Sentence: ";

   getline(cin, user);

   indexfx(user);




   return 0;
}


void indexfx(string sentence)
{
   string vowels = "aeiouy";
   int syllables = 0;

   for(unsigned int i = 0; i < sentence.size(); i++)
   {
      for(unsigned int j = 0; j < vowels.size(); j++)
      {  
         if(sentence[i] == vowels[j]
         {
            syllables++;
         }
      }
   }

   cout << syllables;
}