The Serie A stalemate will be seen as little help to either club's hopes of gaining a UEFA Champions League place for next season and gives Lazio the chance to take third place when it faces second-bottom Pescara on Monday (AEDT).
Milan, for whom Mario Balotelli was a threat in attack, stands third for now, a point ahead of Lazio and Inter but six points adrift of second-placed Napoli.
Stephan El Shaarawy scored the opener for Milan with a dipping left-footed drive in the 21st minute.
But substitute Schelotto made an impact off the bench, heading in after 72 minutes to ensure Inter would not finish empty-handed.
Goals from Paul Pogba, Sebastian Giovinco and Stephan Lichsteiner eased Juventus to a 3-0 home win over Siena and a seven-point lead on idle Serie A title challenger Napoli.
Napoli and fourth-placed Lazio will play their respective matches on Tuesday (AEDT), which handed Juventus the perfect opportunity to distance its title rival against a Siena side fighting for Serie A survival.
Swiss international defender Lichsteiner was on form throughout the day and came close to beating Gianluca Pegolo with a strike which shaved the post in the first half.
Lichsteiner finally got lucky when an angled cross from Andrea Pirlo was parried by Pegolo and the ball bounced off the Swiss and into the net on the half hour.
Siena had few real chances in the match and Italy forward Giovinco virtually put the match beyond reach in the 74th minute when he pounced on the rebound from Pirlo's free kick to double Juve's lead.
Frenchman Pogba put the icing on Juve's performance by toying with the Siena defence on the edge of the area before unleashing a low strike which beat Pegolo at his far post.
Juventus's 18th win in 26 games leaves Antonio Conte's side in control at the top of Serie A with a seven-point cushion on Napoli which travels to Udinese and 14 in front of both AC Milan and Lazio.
Fiorentina's hopes of moving up from sixth place were put on hold after its match at home to Bologna was postponed due to heavy snow.
The winter weather played havoc with preparations for several games, all of which took place under varying conditions.
Roma's visit to snow-hit Bergamo side Atalanta got off to the worst possible start when Croatian teenager Marko Livaja put the host ahead with a superb strike eight minutes in.
Roma levelled through Marquinho's fine individual effort four minutes later and the Giallorossi moved into the lead just after the half hour thanks to Miralem Pjanic's free-kick.
In worsening conditions and with visibility poor, Livaja, 19, restored parity on the stroke of half-time.
Roma looked to be heading for only their fifth draw of the campaign until Greek defender Vassilas Torosidis got on the end of American Michael Bradley's cross in the 71st minute to beat Andrea Consigli in the Atalanta net.
Atalanta finished the match with 10 men after Matteo Contini was given his marching orders two minutes from the whistle for slapping Roma midfielder Simone Perrotta.
Catania maintained its superb campaign with a shock 2-1 win away to Parma which kept the Sicilians in seventh and well within sight of a place in European football next season.
The weekend's shootout, however, took place back on the island where Cagliari claimed a 4-3 win over nine-man Torino.
The match was heading for a 2-2 draw until Torino pair Angelo Ogbonna and Abou Diop were red carded within minutes of each other inside the final 10 minutes.
Mauricio Pinilla stepped up to put the host 3-2 ahead after being fouled by Ogbonna, only for Rolando Bianchi to pull Torino level from the spot minutes later after he was fouled in the area.
Cagliari finally made its two-man advantage count in injury time when Daniele Conti's shot from distance took a deflection off Kamil Glik to leave Jean-Francois Gillet stranded in the Torino net.