The idea of washing the walls is best done with sugar soap. If the odour lingers, you can buy paint that helps to remove odours. Perhaps you can cook and feed some friends in return for them painting the apartment for you?
L'occitane make a small range of air scents that are not sprayed but poured into a small bowl or bottle with pine sticks to wick the liquid up and into the air. My favourite now is the Fig Leaf one. It smells like freshly cut wood, and ends on a very ripe fig note. Not offensive, not girly, covers even salmon cooking! It's a winner for me.
The baking powder works in confined areas, and some supermarkets also sell something similar to remove odours and moisture in the air from cupboards and fridges. One in Australia is sold as Hippo something or other, from memory.
I have heard the vinegar in a bowl works well. Also, dribbling vanilla essence generously onto a loaf of bread and warming it seriously in the oven will fill the house with fragrance that is unlikely to smell like anything other than fresh baking - yummy! You can do the same by sticking oranges with lots of cloves and then rolling the finished ball in mixed spice and leaving around the apartment or hanging from raffia or ribbon to let the air circulate. They can be refreshed with vodka sprinkled over it, and or a little orange oil. I used to love this, but the sticking of cloves must be done with determination - fucking boring and sore thumbs after the first hundred. Get a loving friend or relative to help.

(The oranges are fantastic in the festive season, and also are great by the hearth or stove, if you have one. The scent of oranges is also great for helping to develop an appetite in ill folk.)