Over the past month, rebel factions and the Islamic State have been fighting back and forth on the North Aleppo pocket's eastern frontlines. On 7 April, a coaltion of rebel forces supported by Turkish artillery and U.S. air support captured the town of al-Rai and its border crossing to Turkey. This rebel coaltion included local CIA-vetted FSA groups, such as Sultan Murad, Division 99 etc. and local and national independent Islamist factions, including Jabha al-Shamiyya and Ahrar al-Sham.
An Islamic State counterattack retook al-Rai on 11 April, as well as a number of towns to the west. In an attack during the next week, IS briefly managed to split the rebel pocket in two by taking the town of Hawar Kilis. This attack threatened large camps set up for Internally Displaced People, causing upwards of 30,000 people to flee further west. This attack was eventually repulsed by rebel fighters, who managed to secure Hawar Kilis along the border. Slightly further east, the ethnically Kurdish town of Dudiyan has changed hands multiple times. As of 2 May, it was reportedly under Islamic State control.
On 3 May, after being repeatedly targeted by Turkish shelling, Islamic State imams in the area announced declarations of war against Turkey, threatening the nearby cities of Kilis and Gaziantep.
Also over this period, fighting between the Islamic State and rebel groups around the town of Mare' havs been consistent. Similarly, border skirmishes between rebels and the Syrian Democratic Forces have occurred to the west, over the same time. On 28 April, following a failed rebel assault on the small city of Tel Rifaat, some members of the SDF paraded forty dead rebel bodies through Efrin city streets, causing minor controversy and condemnation by Kurdish leaders.
(Above) The situation in Northern Aleppo, as of 1 April. Since then, IS has claimed to have taken the town of Dudiyan. Source.