Hello!
Please check if you have acquired all the potions Alenar needs. You actually needs five potions, two of which are "Potion of Constitution", based on the information you have given this might be the problem. Once you have them all, you'll receive a journal update informing you that you can return to Alenar. If the problem still persists with all potions in your inventory, please send us a bug report with the Alt + B tool so we can get a detailed look on it.